Signal and test circuit for telephone-exchanges



C. H.. WILSON.

SIGNAL TTTTTTTTTTTT 1T PPPPPPPPPPPPPPP HANGBS.

.No.aog. I n Patented 0010.14, 1884*.'

.UNrrED STATES ATENT OFFICE.

CHARLES H. WILSON, OF CHICAGO, ILLINOIS.

SIGNAL ANDpTEST CIRCUIT FOR TELEPHONE-EXCHANGES.

SPECIFICATION forming -part of Letters Patent No. 306,669, dated October14, 1884.

Application tiled June 20, 1881. (No model.)

T0 @ZZ whom it may concern:

Be it known that I, CHARLEs H; WILSON, of Chicago, Illinois, havediscovered a certain new and useful Improvement in Multiple Switch-BoardSignal land Test Circuits, of which the following is a full, clear,concise, and exact description.

My improvement 'consists in connecting the testing-battery with pointsplaced near the test-keys, so that when the key is depressed and thebattery thrown to line for the purpose of testing, to see if a linewanted is in use at another board, the act of testing will call up thesubscriber, provided his line is not in use.

In the drawings, Figure l is a front elevation of portions of threemultiple switch-boards l, 2, and 3, showing two subscribers7 linesconnected with the switches and test-keys and to ground. Figs. 2 and 3are sections of a fullsized switch and test-key, respectively, uponlines X X and Z Z of Fig. 1.

The switch is of the usual form. lThe test# key consists of the springa, to which the line Y of a subscriber is connected, and two contactpoints, b and c. The telephone-line is normally closed throughcontactpoints b of the test-keys of a line on the different boards toground, as indicated in Fig. l. One pole of the local battery isconnected with the contact-points c of all the test or signal keys, andsignaling-instruments d are provided, as shown. The calls are sent infrom the subscribers stations in any well-known way. I have shownannunciator-needles e in the tele'- phone-lines for receiving the. callsof the subscribers. I find it preferable, however, to

said. spring andthe contact-point c.

my system, when a call is sent in, the switch-l man at the board towhich this call belongs at once presses against spring a of thetest-keyin the line of the subscriber called for. Contact is thus brokenbetween the spring a and contact-point b and a new contactformed betweentery is thus'thrown to line, and the signalinginstrument d in the linebetween the contact- The bat-A point c and-the battery responds,provided the line is not in use, and by simply tapping upon the spring cthe circuit of the line is closed and broken, thus calling up thesubscriber.

I claim- In a' multiple switch-board system, the combination, with thecalling-keys a, of the battery branching to contact-points c and thecontact-points b, whereby any line may be disconnected from its normalground and closed to said battery'upon either of the boards,substantially as specified.

` CHAS. H. WILSON. Vitnesses:

WM. S. GRANGER, GEORGE P. BARTON.

